Table Of ContentRev. Acad. Canar. Cienc, XIV (Nums. 3-4), 201-212 (2002) (publicado en agosto de 2003)
DESCRIPTION OF A NEW SUBSPECIES OF CYMATIUM
(GASTROPODA, RANELLIDAE) FROM THE ATLANTIC OCEAN.
&
Francisco Garcia-Talavera* Alejandro de Vera*
(*) Museo de la Naturaleza y el Hombre, Santa Cruz de Tenerife, Canary Islands
RESUMEN
Se describe Cymatium (Monoplex) comptum amphiatlanticum n. ssp, parael Oceano
Atlantico. Comparandolacon especies similares de su grupo taxonomico como C. comptum
(Adams, 1855), C. indomelanicum Garcia-Talavera, 1997 y C. vespaceum (Lamarck, 1822),
se descubrieron caracteres morfologicos distintivos, pudiendo realizarse una diagnosis diffe-
rencial. En principio, C. comptum amphiatlanticum parece ser similar a C. comptum, pero
tras un estudio exhaustivo de la concha, se aprecian diferencias bien definidas. Todo ello
sugiere que la forma atlantica de C. comptum puede ser considerada, al menos, una nueva
subespecie. Pensamos que ambas tuvieron un ancestro comun procedente del Oceano
Pacifico.
Palabras Clave: Gastropoda, Ranellidae, Cymatium comptum amphiatlanticum,
nueva subespecie, Oceano Atlantico.
ABSTRACT
Cymatium (Monoplex) comptum amphiatlanticum n. ssp. is described in the present
work, from the Atlantic ocean. Comparing it with similar species ofits taxonomic group as
C. comptum (Adams, 1855), C. indomelanicum Garcia-Talavera, 1997 and C vespaceum
(Lamarck, 1822), distinctive morphological characters of the protoconch and teleoconch
were revealed. By doing this, a differential diagnosis was possible. In a first approach, C.
comptum amphiatlanticum seems to be very close to C. comptum, but conspicuous differ-
ences between them are visible after an exhaustive study ofthe shell. This suggest that the
atlantic form of C. comptum can be considered, at least, a new subspecies. We understand
that both had a common ancestor from the Pacific ocean.
Key Words: Gastropoda, Ranellidae, Cymatium comptum amphiatlanticum, new
subspecies, Atlantic ocean.
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INTRODUCTION
1.
The Ranellidae family is well known in the malacological studies for its special
genetic and biogeographical characteristics, making it a very interesting family of
Gastropods. In a previous work, on having described Cymatium indomelanicum (The
Conchiglia, 1997, n° 284) we stressed the importance ofstudying in depth some Ranellidae
species, in order to clear current controversy about them. In this publication we already
explained that the species from the Atlantic Ocean, present in the Canary Island, known at
first as C. gemmatum (Clench and Turner, 1957), lateras C. vespaceum andinthe lastyears
as C. comptum, needed areview, since we were estimating notable differences. We confirm
these differences in this work and conclude that the Atlantic form ofC. comptum is anew
subspecies, that we named Cymatium comptum amphiatlanticum n. ssp.
Thisnew subspecies clearlybelongtothe "C. vespaceumComplex" (BEU [2]). This
complex includes species as C. comptum, C. vespaceum, C. indomelanicum and C. pen-
niketi, due to the numerous characteristics that they share. Even so, the new described sub-
species possess a series of morphologic characters that differentiates it clearly from C.
comptum, the original species ofthis complex with which it can be misidentified.
DESCRIPTION
2.
2.1. Shell description.
Cymatium (Monoplex) comptum amphiatlanticum n. ssp.
mm
Shell ofsmall size (19.15 ofmean), greatly fusiform, with alow spire, and aless
marked or defined whorls in the global context ofthe shell. This causes a not very defined
nodules. Teleoconch with 3.5 - 4 whorls, the last one occupying 3/4 from the whole. Cream
colour (though some specimens may presents orange tonalities, and others are albinos or
melanist, with the peribasal band whitish), with darker dun lines in the varices, which dis-
appear in the rest of the teleoconch. Generally presents only one varix placed in the last
whorl, thin and wide, approximately 240° before the external lip. Relatively short and
straight siphonal channel, lightly curvedin its terminal part. Small, white, narrow and ellip-
tical aperture, with columelars folds fromthe interiorofthe aperture up to the external mar-
gin, and seven pairs of denticles. Thin parietal and columelar calluses, with a well devel-
oped fold in the posterior zone. Smooth, low, wide and robust protoconch, ofyellow - dun
clear and dull colour. Ornamentation consisting ofaprincipal spiral cord moderately width,
and a thinner secondary spiral cord between every principal one. Thin and definite axial
cords that cause a few granulations in its intersection with the spiral cords. Although being
enough small in size, they are very marked and well defined, especially in the principal spi-
ral cords. Smooth andbrilliantperiostracum, presenting relatively shorts and thinhairiness-
es with axial disposition, in protuberances, varix and external lip. Oval operculum with api-
cal growth.
We also thinkthatis necessary to leavewitness ofthe appearance ofsome specimens
of melanistic forms ofC. comptum amphiatlanticum. The shell presents a very darkbrown
color, excepting a whitish part which comprehends varix, external lip and the peribasal
202
band. This pattern ofcoloration is alike the typical one which has C. indomelanicum, which
canleadamisidentificationwiththis species. In anycase, detailedobservations confirmthat
these melanistic specimens belong to C. comptum amphiatlanticum, since, apart from the
pattern of coloration, they do not present practically any morphologic difference with the
original form.
So far, this melanistic formhas only been found in the Western coast ofthe Atlantic
Ocean, concretly in Cuba, and also its presence has been confirmed in Brazil (DOS SAN-
TOS, RAMOS & LEAL [6]). Nonetheless, we do not discard that this form can have an
amphiatlantic distribution, due to its location in the system of streams circulation of the
above mentioned ocean (GARCIA - TALAVERA [9]).
2.2. Distribution
IntheWesternAtlantic, throughtheCaribbeancoast, inFlorida (CLENCH &TURN-
ER, [4]), Cuba, Venezuela and Brazil (DOS SANTOS, RAMOS & LEAL [6]; RIOS [14]),
where the Holotype and Paratypes were dredged, and in the Eastern Atlantic, at the Cape
Verde Islands (SAUNDERS [15]) and the Canary Islands (GARCIA - TALAVERA [8]).
2.3. Type Material
Holotype (Fig. 1) from Pompano Beach, Florida, Paratypes 1, 2, 3, 4 from
Cienfuegos, Cuba; Paratypes 5, 6, 7 from Ensenada de Maya, Cuba; Paratype 8 from Los
Roques, Venezuela; Paratype 9 from La Habana, Cuba; and Paratype 10 from Port Luis,
I. Guadalupe (Fig. 3).
Holotype and Paratypes 1, 3, 4, 5, 6, 8, 9, 10 are deposited at the Type Collection
of Marine Mollusca of Museo de la Naturaleza y el Hombre (MNH), Tenerife, Canary
Islands. Paratype 2 will be deposited at British Museum ofNatural History (BMNH), and
Paratype 7 at the New Zealand Geological Survey (NZGS).
2.4. Etymology
We namedamphiatlanticum, thenew subspeciesforthe Atlantic ocean, forbeingone
of the Ranellidae species which lives in the two margins (oriental and occidental) of this
ocean.
MORFOMETRY AND COMPARED STATISTICS
3.
Trying to establish the morphological differences between every species, the shell
MNH
dimensions of a whole of 31 specimens of the collection were analyzed, of which
18 correspond to the typical form ofC. comptum, and 13 ofC. comptum amphiatlanticum
form.
To make this dimensions comparable, they were calculated measuring only the teleo-
conch, without including the protoconch and the siphonal channel. This was done due to the
possible absence for the total or partial loss ofthese elements in some ofthe analyzed spec-
imens. Taking this pattern of measurement, the possible influence and the consequent mis-
203
take that would cause these specimens in the analysis is
eliminated, due to the difference of lengths for extrinsic
reasons ofthese elements excluded from the analysis.
The setofmeasurements estimatedforevery spec-
imen ofeach one ofthe two species is as follows:
- Teleoconch Length (L).
- Teleoconch Wide (W).
- Last Whorl Length (LLW).
- Aperture Length (AL).
- Aperture Wide (Aw).
3.1. Dimensions (in mm)
Cymatium comptum (Adams, 1855)
W
Locality L Llw AL Aw
Calitoban IsL, PHILIPPINES 27 18 19 10 5
Calitoban IsL, PHILIPPINES 21 15 16 9.5 5
Calitoban IsL, PHILIPPINES 19 13.5 14 7 4
Mactan IsL, Cebu, PHILIPPINES 25.5 16.5 17 10 5.5
Mactan IsL, Cebu, PHILIPPINES 23.5 17 18 10 5.5
Mactan IsL, Cebu, PHILIPPINES 23 16 16 10 5.5
Mactan IsL, Cebu, PHILIPPINES 24.5 15 17 9.5 5
Mactan IsL, Cebu, PHILIPPINES 22 15 15.5 9 5
Mactan IsL, Cebu, PHILIPPINES 18 12.5 13.5 8 4.5
Mactan IsL, Cebu, PHILIPPINES 17.5 13 13.5 7.5 4
Mactan IsL, Cebu, PHILIPPINES 20 14.5 14.5 9 5
Phuket, THAILAND 23 15 16.5 9.5 5.5
Minake, JAPAN 23.5 14.5 17 9.5 5
Bohol, Cebu, PHILIPPINES 23.5 16 16.5 10 5.5
Bohol, Cebu, PHILIPPINES 21 14 14.5 8 4.5
CENTRALPHILIPPINES 20 13 14.5 9 5
CENTRAL PHILIPPINES 18 13 13.5 9 5
VIETNAM 22.5 16 16 8.5 5
MEAN
21.81 14.86 15.69 9.06 4.97
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Cymatium comptum amphiatlanticum n. ssp.
W
Specimen Ljy L Ww AL Aw
Holotype 20 15.5 11.5 12 7 3.5
Paratype 1 17 11 8 9 5.5 2.5
Paratype 2 20 15 10 11.5 6 3
Paratype 3 17 13 8.5 10.5 5.5 2.5
Paratype 4 16.5 13 9 10 6 2.5
Paratype 5 18 13.5 9 10.5 5 2.5
Paratype 6 22 17.5 12 13.5 8 3.5
Paratype 7 20.5 16.5 11 12 6 3
Paratype 8 19.5 15 11 11.5 8 4
Paratype 9 17 13.5 9.5 10.5 6.5 3
Paratype 10 18.5 15 10 11.5 6 3
1251 /BocaRaton, FLORIDA 18 22.5 15.5 16.5 10 5
1260/Ensenadade Maya, CUBA 25 17.5 11.5 13.5 7.5 3.5
MEAN
19.15 15.27 10.5 11.73 6.69 3.19
To solve the difficulty of making these dimensions (considered as principals) com-
parable, due to the size differences between both species to be analysed, a series of
Secondary orRelativeDimensions was calculated, fromthese, which make the comparisons
possible. They are the confirmed ones in the posterior statistical study:
- Relative Last Whorl Length (LLW /L)
- Relative Teleoconch Wide (W /L)
- Aperture Widening (Aw/AL)
- Aperture Size (JAw x Al/L)
Obtained Means for each species are:
SPECIES LLVV /L W/L AW/AL -JAw x Al/ L
C. comptum 0.7219 0.68 0.5499 0.3095
C. comptum amphiatlanticum 0.7714 0.6885 0.4762 0.3017
3.2. Statistical Analysis
Using the dimensions of the specimens detailed, a parametric statistical study was
carried out, based on a Student's-t Test distribution with a 95% of significance. This was
done to contrast whether significant differences exist in the relative dimensions, and there-
fore in the detailed morphology ofthe shell between each of the two species to analyse. In
spite of possessing few specimens to carry out a totally irrefutable analysis, we think that
the Student's-tTest distribution is attainable for this sample size. The results of the contrast
are detailed as follows:
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- With respect to the general teleoconch size, a less Teleoconch Length (L) of C.
amphiatlanticum in relation with C. comptum is significant.
- Respecting to the Relative Last WhorlLength (LLW / L), there is verified that C.
comptum amphiatlanticum possesses a major significant value that C. comptum.
- With respect to the Relative Teleoconch Wide (W / L), C. comptum amphiat-
lanticum and C. comptum, does not present significant differences.
- With regard to the Aperture Widening (Aw / AL), C. comptum amphiatlanticum
presents a very much minor widening that in C. comptum.
- Respecting to the Aperture Size (JAw x Al / L), we do not find significant dif-
ference between any ofthe two species.
3.3. Statistical Conclusions
Having present these statistical results, we can conclude that C. comptum amphiat-
lanticum has, in general, a minor size and a more compact and flattened spire. It presents
also anarrower, elliptical andelongated aperturethan C. comptum, occupyingthelastwhorl
77 % ofthe total length ofthe shell. In turn, its aspect is more fusiform and with the least
marked whorls.
COMPARATIVE DIAGNOSIS
4.
As we already mentioned in the introduction, C. comptum is the species which can
lead to some type of morphologic misidentify comparing it with the new described sub-
species. Nonetheless, these have a series ofcharacteristics that make it clearly distinguish-
able. Already in SPRINGSTEEN&LEOBRERA [19] andinBEU [2], were definitethedif-
ferences between C. comptum and C. vespaceum clearly.
C. comptum amphiatlanticum has generally a minor size, narrower aperture and a
shorter siphonal channel than C. comptum, as well as a more fusiform aspect and a lower
spire. In turn, the color is much clearer, having a cream and yellow tonality. Also, the pro-
toconch of C. comptum amphiatlanticum is lower, broad and thinner, ofdull aspect and of
minortransparency. The differences are appreciated even in the firstlarval whorl, being this
lower and wider than in C. comptum. As for the ornamentation, C. comptum amphiat-
lanticum posses in the majority ofthe analyzed specimens, only a thinner secondary spiral
cord, between every principal cord. These characteristics are unlike C. comptum, that pres-
ents even three spiral cords. Besides, the axial cords are more defined and separatedthan in
C. comptum. They cause, in its intersection with the spiral cords, a few major granulations
and also more definite and separated in C. comptum amphiatlanticum. Also, the protuber-
ances or spiral nodules are less accused, forming less marked shoulders, though there is less
space between them, and therefore, they are in a major number than in C. comptum. This
characteristic is clearly observed from an apical position. Likewise, C. comptum amphiat-
lanticum has only one varix, thicker enough, unlike the thinner three as minimum of C.
comptum. This varix is dorsally displeased, whereas the equivalent one in C. comptum is
nearer from the columelar edge. Finally, the apertural teeth are thinner and closer in C.
comptum amphiatlanticum, probably due to the narrower aperture that it has, having less
space for its insertion. Besides, the peristoma is more folded, standing out less towards the
exterior than in C. comptum, having it more widespread, starting to invade even lightly the
external lip in this last species.
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BIOGEOGRAPHICAL CONSIDERATIONS
5.
Until afew years ago, Cymatium vespaceum (Lamarck, 1822) was appearing as one
of the cosmopolitan species of tropical waters belonging to the family Ranellidae
(=Cymatiidae). After the investigations of the last two decades, this species has been
removedinnew others, giving originto whatitis known as "C. vespaceum Complex"(BEU
[2]). This complex includes at least 6-7 species: C. vespaceum, C. comptum, C. indome-
lanicum, C. penniketi, another new species that we will describe soon from Mozambique,
and the new subespecies described here: C. comptum amphiatlanticum. Two of these (C.
vespaceum andC. comptum) liveinthewesternPacific Ocean, three inthe Indian ocean (C.
vespaceum, C. penniketi, C. indomelanicum), whereas only one (C. comptum amphiat-
lanticum) lives in the Atlantic Ocean, (though C.vespaceum seems that it appears sporadi-
callyinthis ocean (PIECH [13]). Therestricteddistributionofthe species ofthis "complex",
which live in the Indian Ocean, have us to think that the center ofirradiation and the com-
monancestorofall ofthemwasinsometropicalregionoftheWestPacific Ocean. Probably,
it began its dispersion towards the Indian and the Atlantic Ocean in the Pliocene, with suc-
cessive connections and desconnections of genetic flow caused by the alternates climatic
changes. This happened fundamentally during the Quaternary, when the deflections of the
paths ofthe marine cold and hot streams played an important role in the phenomena ofdis-
persion, genetic flow and speciation ofmany ofthe current species.
In the case of C. comptum amphiatlanticum, we think that the ancestral form pene-
trated in the system of Atlantic Ocean circulation during some interglaciar epoch of the
Lowest Pleistocene, across Agulhas's stream in South Africa, in which the Benguela's cold
stream moderated and allowed its introduction.
ACKNOWLEDGEMENTS
6.
The authors are very thankful to Sergio Socorro, from Museo de la Naturaleza y el
Hombre, for the illustrations; to Dr. Luis De Vera, from Universidad de La Laguna
(Tenerife), for supports the statistical analysis and the English revision; and to Fernando
Martin, for the final English corrections made in this work.
207
ILLUSTRATIONS
7.
Fig. 1: HolotypeofCymatium (Monoplex)comptumamphiatlanticumn. ssp. VentralandDorsalview.
Fig. 2: Comparison between C. comptum amphiatlanticum and C. comptum protoconchs. Note the differences
betweenwhorlsmorphology.
208
Fig.3: Fromlefttorightside,Paratypes6and7andHolotypeofCymatium(Monoplex)comptumamphiatlanticum
n. ssp. (firstrow), comparing with three small specimens ofthe Indo - West Pacific typical form ofC. comptum.
(second row).
>09
Fig.4: ParatypesofCymatium (Monoplex)comptumamphiatlanticumn. ssp
210
